Bangkok: The foreigner accused of planting a bomb at a Bangkok shrine has admitted involvement in the deadly attack, his lawyer said Wednesday, reversing earlier denials of a confession.

The comments by lawyer Schoochart Kanpai confirmed the Thai authorities` version of the complex investigation into the August 17 blast which killed 20 people.

Earlier this week Schoochart had questioned whether the man -- whom police have named both as Bilal Mohammed and as Adem Karadag -- had confessed.

The lawyer said his client had previously insisted he was not in the country on the day of the attack.

But after meeting his client on Wednesday, Schoochart reversed his position.

"I met Adem this morning for about an hour and he said he confessed voluntarily to planting the bomb," the lawyer told reporters outside the military barracks in central Bangkok where the accused is detained.

It was not immediately clear if authorities were present during the Wednesday meeting.

On Saturday police said they were now convinced that Mohammed, the first person to be arrested, was the same man seen in CCTV footage wearing a yellow T-shirt and placing a backpack at the Erawan shrine moments before the explosion.

They said his confession, together with other security camera footage and eyewitness accounts, confirmed they had the right man -- after earlier saying DNA evidence suggested it was unlikely to be him.

Police say they believe the man in the yellow shirt wore a wig and glasses to disguise himself.

In a briefing on Monday, investigators released a series of four sketches showing how Mohammed could have transformed his appearance from the initial suspect sketch which showed a man with glasses and floppy hair.

The suspect now appears more gaunt and with a shaven head.

In other new details of the still unclaimed attack, Schoochart said Mohammed relayed how he followed orders from another man, Abdulah Abdullahman, and was unpaid.

Abdullahman is among more than a dozen other people -- both foreigners and Thais -- wanted over the blast. Only two men -- Mohammed and another man named as Yusuf Mieraili -- are in custody.

Mystery still shrouds the motive for the unprecedented attack, in which the majority of fatalities were ethnic Chinese tourists.

Speculation has centred on a link to militants or supporters of the Uighurs, an ethnic group who say they face severe persecution in China, after Thailand forcibly repatriated 109 of the minority in July.

The move sparked international condemnation, particularly in Turkey where hardliners see the minority as part of a global Turkic-speaking family.

According to his lawyer, Mohammed is a Chinese Uighur who settled in Turkey while Mieraili is a Chinese passport-holder with Uighur ethnicity.

Thai authorities have not confirmed the nationality of either man. They say they believe the blast was revenge for a crackdown on people-smuggling gangs whose operations include the transfer of Uighurs.